Bilateral Superior Cervical Ganglionectomy Research Articles

Effects of acute superior cervical ganglionectomy on cerebral blood flow and metabolism in stroke-prone spontaneously hypertensive rats subjected to cerebral ischaemia.

1. The effects of acute bilateral superior cervical ganglionectomy on cerebral blood flow and metabolism were investigated in stroke-prone spontaneously hypertensive rats (SHRsp), before and during cerebral ischaemia. 2. The resting cerebral blood flow was comparable between the control and denervated animals. 3. There was no significant difference in cerebral blood flow or concentration of tissue energy metabolites (adenosine triphosphate [ATP], lactate and pyruvate) between the sham-operated control and denervated animals during ischaemia. 4. The results suggest that sympathetic innervation of cerebral vessels originating from superior cervical ganglia may not play a major role in the progression of cerebral ischaemia in SHRsp.

Short-day stimulation of testicular activity and immunoreactivity of the hypothalamic GnRH system in mink following deafferentation of the pineal body by bilateral superior cervical ganglionectomy and melatonin replacement

The effects of superior cervical ganglionectomy on testicular function (testis volume and plasma testosterone levels) and the immunocytochemical activity of the GnRH hypothalamic system were studied in the mink, a short-day breeder. Animals reared in a natural photo-period were (i) ganglionectomized at four different times during the period extending from the end of summer to the end of autumn (September 15, October 20, October 28, and December 1), and (ii) reared for 50 days in a short gonadostimulatory photoperiod (4L:20D). Lastly, an attempt was made to overcome the effects of superior cervical ganglion removal by administering melatonin to mink reared in a natural photoperiod. In mink reared in a natural photoperiod, deafferentation of the pineal on September 15 ( L= 12.5h) or October 20 ( L= 10.5h) resulted in consistently low values of testicular volume and plasma testosterone until the end of the experiment (February). When the operation was performed on October 28 ( L= 10h) testicular activity was initiated but only lasted a short time and did not allow maximal gonadal development. When superior cervical ganglionectomy was carried out on December 1 ( L= 8.5h), during the phase of renewed testicular activity, the increases in testicular volume and testosterone levels were not affected by the operation and the subsequent variation of these parameters was identical to that observed in intact animals. Similarly, in mink reared for 50 days in a photoperiod of 4L:20D before superior cervical ganglionectomy, deafferentation of the pineal did not prevent gonadostimulation induced by short days. These results show that once the hypothalamic system secreting GnRH is triggered by short days, its activity is no longer controlled by the photoperiod. The immunohistochemical study of GnRH-secreting hypothalamic neurons, carried out in December without prior colchicine treatment in animals ganglionectomized in September or October, showed the presence of only a small number of GnRH-positive perikarya. Similarly, positive axonal endings in the external layer of the median eminence were scarce and weakly immunoreactive. On the other hand, in intact animals, in those ganglionectomized on December 1, and those exposed to the short photoperiod of 4L:20D, perikarya and immunoreactive endings were numerous and intensely labeled. In mink ganglionectomized in October ( L= 10.5h) and thereby maintained in a phase of sexual quiescence, insertion of melatonin implants in January triggered testicular activity 50 days later.

The superior cervical ganglia are not necessary for entrainment or persistence of the pineal melatonin rhythm in Japanese quail

The avian pineal exhibits a daily rhythm in the synthesis and secretion of the hormone, melatonin, which is involved in maintaining temporal order within the circadian system of some species. The pineal is richly innervated by sympathetic nerves which originate in the superior cervical ganglia (SCG) and, in the chicken, these nerves play a role in generating the melatonin rhythm. In the Japanese quail, the pineal melatonin rhythm can be entrained by light perceived directly by the pineal or by light perceived by the eyes. The role of the sympathetic innervation of the pineal was investigated in the Japanese quail by subjecting birds to bilateral superior cervical ganglionectomy (SCGX) and determining if SCGX either abolished the ability of retinally perceived light to entrain the pineal melatonin rhythm or if it disrupted the rhythm under constant darkness (DD). The results show that SCGX neither prevented entrainment of the pineal melatonin rhythm by retinally perceived light nor affected the rhythm expressed in DD. An entrainment pathway between the eyes and pineal exists in quail which does not involve the SCG.

Pineal melatonin concentrations during day and night in the adult hedgehog: Effect of a light pulse at night and superior cervical ganglionectomy

The European hedgehog (Erinaceus europaeus L.) is a hibernating mammal and seasonal breeder in which numerous circadian and circannual rhythms are entrained and synchronized by photoperiod. The present study was undertaken in order to establish the involvement of the pineal gland in transducing the photoperiodic message in this species. Pineal melatonin concentrations were determined by radioimmunoassay in female hedgehogs kept under natural climatic conditions and killed during the light:dark (L:D) cycle in spring and autumn, after the interruption of darkness by a 45 min light pulse, and after bilateral superior cervical ganglionectomy (SCGx). Absolute melatonin concentrations were low (less than 100 pg/pineal) in the pineal gland. Under natural climatic conditions, in spring and in autumn, pineal melatonin concentrations exhibited a marked diurnal rhythmicity, with very low levels in the day (1200: less than 10 pg/pineal) and high levels during the night (2200: 71.9 +/- 18.6 pg/pineal; 0200: 42.5 +/- 15.6 pg/pineal). The 45 min light pulse during darkness depressed rapidly and significantly the melatonin content (dark + light [D + L]: less than 10 pg/pineal), but a subsequent return to darkness restored high melatonin content after approximately 2 h (D + L + D: 65.4 +/- 20.2 pg/pineal). After bilateral SCGx, melatonin concentrations were reduced and no increase during night could be observed, either in animals sacrificed 42 days after SCGx or in animals killed 2 years after SCGx. In the hedgehog, as in other mammals, pineal melatonin concentrations are related to the light:dark cycle. Such data indicate that during the year, in this species, the effects of light on seasonal endocrine rhythms may be mediated by the pineal gland.

Anterograde Nerve Degeneration after Superior Cervical Ganglionectomy Coexists with a Decrease in Arginine Vasopressin Release in Rats

After bilateral superior cervical ganglionectomy (SCGx) in adult male rats, norepinephrine content of the pituitary neurointermediate lobe (NIL) decreased at 12-24 h after surgery to attain concentrations 40-60% of controls between 24 and 60 h after surgery. To assess arginine vasopressin (AVP) secretion during this time, plasma and NIL-AVP levels were measured by radioimmunoassay. In sham SCGx controls, plasma AVP increased about 2-fold within 6 h after surgery and decreased thereafter, to attain presurgical values by 60 h after surgery. In SCGx rats, a significant increase in plasma AVP concentration was observed at the 6th h after surgery, as compared to presurgical concentrations, with a decrease to values significantly lower than those of presurgical controls at 16-18 h after SCGx. As compared to sham-operated rats, significantly higher plasma AVP levels 6 h after surgery and significantly lower plasma AVP levels 16-24 h after surgery were found. NIL-AVP concentration in SCGx and sham-operated ras were significantly lower than presurgical levels at 6 h after surgery. SCGx rats had significantly higher amounts of AVP in NIL at 16-24 h after surgery. The changes in plasma and NIL-AVP levels found 6 or 16 h after SCGx or sham SCGx were unaffected by a prior pinealectomy. Two injections of the alpha 1-adrenoceptor blocker prazosin 45 and 90 min before sacrifice, alone or together with the beta-blocker propranolol, prevented the increase in plasma AVP found in SCGx rats 6 h after surgery, and the decrease in plasma AVP and the increase of NIL-AVP found 16 h after SCGx.(ABSTRACT TRUNCATED AT 250 WORDS)

Immunohistochemical Localization of [Met 5]enkephalin and [Met 5]enkephalin-Arg 6-Gly 7-Leu 8 in sympathetic and parasympathetic neurons and nerve fibers projecting to the rat submandibular gland

The localization of [Met 5]enkephalin, [Met 5]enkephalin-Arg 6-Gly 7-Leu 8, vasoactive intestinal polypeptide and tyrosine hydroxylase immunoreactivities was studied in the submandibular gland of adult Sprague-Dawley and Wistar rats using the indirect immunofluorescence technique. Immunoreactivities for [Met 5]enkephalin and [Met 5]enkephalin-Arg 6-Gly 7-Leu 8, a proenkephalin A-derived octapeptide, showed identical distributions. A large number of enkephalin-immunoreactive nerve fibers were detected around secretory acini, along intercalated ducts, convoluted granular tubules, intra- and interlobular ducts, as well as in close contact with blood vessels. The submandibular ganglia contained several enkephalin-immunoreactive neurons and nerve fibers. In the superior cervical ganglion numerous enkephalin-immunoreactive neurons and nerve fibers were also detected. Immunohistochemical co-localization studies indicated that [Met 5]enkephalin and [Met 5]enkephalin-Arg 6-Gly 7-Leu 8 immunoreactivities co-exist with vasoactive intestinal polypeptide in a subpopulation of neurons of the rat submandibular ganglia, in nerve trunks along the salivary ducts of the gland, and in nerve fibers around the acini. Uni- or bilateral superior cervical ganglionectomies for 1–4 weeks resulted in a complete disappearance of tyrosine hydroxylase immunoreactivity in the glandular parenchyma, while moderate tyrosine hydroxylase immunoreactivity was seen in some neurons of the submandibular ganglia. Abundant [Met 5]enkephalin-Arg 6-Gly 7-Leu 8-immunoreactive nerve fibers were still seen around the acini and blood vessels, as well as close to salivary ducts. These operations did not affect the [Met 5]enkephalin-Arg 6-Gly 7-Leu 8-immunoreactive neurons in the submandibular ganglia. Many principal neurons in the superior cervical ganglion contained both [Met 5]enkephalin-Arg 6-Gly 7-Leu 8 and tyrosine hydroxylase immunoreactivity. Nerve ligation experiments indicated that [Met 5]enkephalin-Arg 6-Gly 7-Leu 8-immunoreactive sympathetic fibers project along the external carotid nerve. Accordingly, nerve fibers were found around the acini and blood vessels as well as in nerve trunks along the salivary ducts of the submandibular gland, showing co-localization of [Met 5]enkephalin-Arg 6-Gly 7-Leu 8 and tyrosine hydroxylase. Taken together, these observations suggest that the nerve fibers of the rat submandibular gland containing proenkephalin A-derived peptides are of both sympathetic and parasympathetic origin.

Marked antiinflammatory effects of decentralization of the superior cervical ganglia.

Intravenous challenge with parasite antigens in Nippostrongylus brasiliensis-sensitized rats resulted in anaphylactic shock and, in some animals, death. Surviving animals showed significant drop in mean arterial blood pressure, cardiac output, and blood flow to the trachea, bronchioles, and mesentery. After anaphylaxis, changes in the cellular and protein composition in bronchoalveolar lavage fluids (BALF) were assessed. 8 h after antigen challenge, there was significant influx of inflammatory cells and an increase in the levels of histamine and serum-derived immunoglobulins (IgG and IgM) in BALF. Chemotactic activity for neutrophils was also present in BALF. Once we established this anaphylaxis-induced model of pulmonary inflammation, we sought to determine whether or not the superior cervical ganglia (SCG) modulate this inflammation. We performed bilateral superior cervical ganglionectomy or decentralization of the SCG. Our results show that decentralization significantly reduced mortality (by 68%) after anaphylaxis. Furthermore, the increases in levels of serum-derived proteins, histamine, and influx of cells (especially neutrophils) observed in BALF after anaphylaxis were attenuated by both decentralization and ganglionectomy. By contrast, hemodynamic parameters in the respiratory tract and the presence of neutrophil chemotactic activity in BALF were not influenced by decentralization. Thus, the severity of pulmonary inflammation initiated by systemic anaphylaxis is depressed by bilateral ganglionectomy or decentralization of SCG.

Reorganization of cranial sympathetic pathways following neonatal ganglionectomy in the rat

Postganglionic sympathetic innervation normally is distributed ipsilaterally to lateral cranial targets. However, contralateral outgrowth occurs following unilateral ganglionectomy in neonatal rats. This study was conducted to determine the prevalence, morphological features, ganglionic derivations, and temporal sequence of sympathetic reinnervation of denervated cranial targets. Unilateral superior cervical ganglionectomy of mature rats revealed exclusively ipsilateral distributions of catecholaminergic histofluorescent fibers to orbital targets (Meibomian gland, tarsal muscle, orbital muscle, iris, ciliary body, vasculature) and the circle of Willis, with the exception of the anterior cerebral artery. In mature rats following neonatal unilateral ganglionectomy, all targets were reinnervated by fibers displaying morphologies and target relationships similar to normal innervation, but with lower densities. Acute excision of the remaining superior cervical ganglion eliminated all fibers in 7 of 8 preparations. In adult rats receiving neonatal bilateral superior cervical ganglionectomies, cerebral vasculature was reinnervated consistently, and orbital targets contained fluorescent fibers in 6 of 16 cases, indicating that reinnervation can derive from other sources when superior ganglion outgrowth is prevented. Observations in developing rats revealed fibers along the cranial portion of the contralateral optic nerve sheath at 2-3 days postganglionectomy, and within the orbit at later ages, reaching the most distal targets by 14 days. It is concluded that widespread sympathetic reinnervation of orbital and cerebrovascular targets derives primarily from the contralateral superior ganglion. Orbital ingrowth apparently originates intracranially and enters the orbit by an atypical pathway within the optic foramen.

Synaptic junctions between sympathetic axon terminals and pinealocytes in the monkey Macaca fascicularis

The distribution of axon terminals in the pineal gland of monkeys was studied by electron microscopy. Numerous terminals bearing small pleomorphic agranular and dense-cored vesicles were localized in the perivascular space and among the pinealocytes in the parenchyma in normal monkeys. Following bilateral superior cervical ganglionectomy, they underwent degenerative changes, including the accumulation of glycogen masses, appearance of dense residual bodies and the displacement of synaptic vesicles. Some of these degenerating terminals showed synaptic contacts with the cell bodies of pinealocytes. At the synaptic junction the postsynaptic membrane was thickened asymmetrically. Examples of synaptic contacts were most frequently observed in 5 and 7 days postoperative animals. In the longer surviving (30 days) monkey, most of the axon terminals showed round agranular vesicles, and they were mainly presynaptic to the intrapineal ganglion cells with some of the pinealocytes. They remained structurally unchanged following the resection of both the superior cervical ganglia. A few axon terminals containing small dense-cored vesicles appeared to have survived the initial insult, but some of their vesicles appeared swollen 30 days after the operation. It is concluded from this study that some of the pinealocytes are under the influence by the postganglionic neurons in the superior cervical ganglia through direct synaptic contacts. The intrapineal ganglion cells are postsynaptic to fibres originating exclusively from the central nervous system. Some of these fibres, however, may be presynaptic directly to pinealocytes.

Nerve growth factor receptor in neural lobe of rat pituitary gland: immunohistochemical localization, biochemical characterization and regulation

Nerve growth factor-receptor immunoreactivity was detected in the neural lobe of the pituitary gland in developing and adult rats of both sexes. The presence of nerve growth factor receptor in the neural lobe was further verified by a quantitative 125I-nerve growth factor/crosslink/immunoprecipitation assay and subsequent visualization by SDS-PAGE autoradiography. Nerve growth factor-receptor immunoreactivity was detected in the neural lobe of postnatal 5-day-old rats, had increased by 2 months and was much higher in 1-year-old rats. In 2-month-old rats, no immunoreactivity was observed in anterior or intermediate lobes. Pituitary stalk transection in young adult rats greatly increased the expression of nerve growth factor-receptor immunoreactivity in the neural lobe, although the staining pattern remained the same. This increase began 3 days after surgery, and reached peak levels at approximately 15 days. Other physiological or non-physiological changes did not alter the nerve growth factor-receptor immunoreactivity in the neural lobe; these changes included dehydration, pregnancy and lactation, castration of male rats, bilateral superior cervical ganglionectomy and intraventricular injection of colchicine. Intravenously injected 125I-nerve growth factor was specifically accumulated in both normal and denervated neural lobe. Nerve growth factor-receptor immunohistochemical electron microscopy showed that the receptor-positive cells are fusiform and found both inside and outside the basal lamina that delimits the neural lobe parenchyma. Based upon the anatomical localization, morphology and response to axotomy, we identify, at least the perivascular component, as microglia. These data suggest a role for nerve growth factor and/or nerve growth factor receptor in microglial function.

Differential Effects of Electrical Stimulation of the Dorsal Raphe Nucleus and of Cervical Sympathectomy on Serotonin and Noradrenaline Concentrations in Major Cerebral Arteries and Pial Vessels in the Rat

The levels of noradrenaline (NA), serotonin (5-HT), and 5-hydroxyindoleacetic acid were measured by HPLC and compared between the large arteries of the circle of Willis and the small pial vessels in the rat, following either electrical stimulation of the dorsal raphe nucleus or bilateral superior cervical ganglionectomy. With electrical stimulation, the 5-HT concentrations were reduced (-48%) in the small pial vessels, but were unchanged in the major cerebral arteries. NA concentrations were dramatically reduced following cervical sympathectomy in the large arteries (-77%), though the reduction was less pronounced (-34%) in the small vessels. Sympathectomy caused a significant decrease in the 5-HT concentration of the major cerebral arteries (-33%), but was without effect on the 5-HT levels of the small pial vessels. These results show that an appreciable fraction of the perivascular 5-HT measured in the small pial and the large cerebral arteries originates from different sources.

Serotonin uptake into cerebrovascular nerve fibers of rat, visualization by immunohistochemistry, disappearance following sympathectomy, and release during electrical stimulation

Immunohistochemistry as well as in vitro uptake and release of [ 3H]5-HT were performed on pial arteries of rat to investigate the nature of 5-HT containing nerve fibers. Immunoreactive fibers were constantly found only in the basilar, vertebral and superior cerebellar arteries, while in the other parts of the circle of Willis, 5-HT immunofluorescent fibers were absent. After systemic treatment with tryptophan following inhibition of monoamine oxidase with nialamide the immunofluorescence intensity was markedly enhanced. The 5-HT immunoreactive fibers disappeared after superior cervical ganglionectomy or intraventricular administration of 6-hydroxydopamine, but persisted after administration of 5,6-dihydroxytryptamine. When isolated vessels were incubated in low concentration of 5-HT (1 nM) together with nialamide, a very dense plexus of 5-HT immunoreactive fibers appeared in all branches of the circle of Willis. Uptake and release experiments were carried out by incubation of arterial preparations with 3 nM [ 3H]5-HT (together with nialamide), followed by electrical field stimulation, or by exposure to tyramine or 124 mM potassium, all of which induced a 100%–350% increase in the tritium release over prestimulation values. Preincubation with cocaine and bilateral superior cervical ganglionectomy abolished or markedly attenuated the release upon all modes of stimulation. The results suggested that the 5-HT observed by immunohistochemistry in pial arteries is located in sympathetic nerve terminals where it may serve as a neuromodulator that is released during nerve activation.

Cholinergic stimulation of phosphoinositide hydrolysis in the rat pineal gland

Carbachol induced a dose-dependent accumulation of inositol monophosphates in the Wistar rat pineal gland. The relative potency of muscarinic antagonists (atropine > pirenzepine ⪢ gallamine) in blocking this response suggests the involvement of muscarinic M 1 receptors. Following bilateral superior cervical ganglionectomy, the carbachol-induced phosphoinositide response was similar to that seen in sham-operated controls, while adrenergic response was enhanced by 50%. The results indicate that the pineal has functional muscarinic receptors which are not affected by removal of the sympathetic innervation to the gland.

Cervical sympathectomy and cerebral microvascular and blood flow responses to hypocapnic hypoxia

This study evaluated the effects of bilateral superior cervical ganglionectomy on cerebral blood flow (CBF) and utilization of brain capillary reserve in conscious rats during normoxia and hypoxia (8% O2 in N2). Regional CBF was determined in sham-lesioned and ganglionectomized rats with [14C]iodoantipyrine. The percentage of the total volume fraction and number of perfused capillaries was determined by comparing the perfused microvessels, identified by the presence of fluorescein isothiocyanate dextran, with the total microvascular bed, identified by alkaline phosphatase stain. There were no significant differences in regional CBF between control and ganglionectomized rats under normoxic conditions. CBF increased significantly during hypoxia in both control and control ganglionectomized rats. In control, hypoxic flow to caudal structures was significantly higher than to rostral structures and that differential response was prevented by ganglionectomy. There was no significant difference in the number of perfused microvessels between sham-lesioned and ganglionectomized rats during normoxia. The number of perfused arterioles and capillaries was significantly higher under hypoxic conditions than under normoxic conditions in sham and ganglionectomized animals. During hypoxia, the percent of arterioles per squared millimeter perfused increased to 63 +/- 5% in sham-lesioned rats and to a significantly greater extent, 80 +/- 6%, in ganglionectomized rats. The percentage of capillaries per squared millimeter perfused changed similarly. The peripheral sympathetic nervous system appeared to play an important role in the control of cerebral microvascular response to hypoxia.

5-Hydroxytryptamine-Containing Fibers in Cerebral Arteries of the Cat, Rat and Guinea Pig

The distribution of serotonin-like immunoreactive (5-HT-LI) fibers in pial arteries and arteries of the choroid plexus in the cat, rat and guinea pig was examined. Weak 5-HT-LI fibers were observed in cerebral arteries when these arteries were fixed by immersion after they had been dissected from the exsanguinated animals. The 5-HT-LI fibers, however, were not detected in arteries when they were fixed in situ or in vitro after they had first been perfused with phosphate-buffered saline (PBS) or Krebs solution in situ to flush the blood components from the lumen prior to dissection. In these arteries, 5-HT-LI fibers with intense immunofluorescence could however be demonstrated following incubation with serotonin (5-HT) in vitro. The distribution patterns of 5-HT-LI fibers and catecholamine fluorescence fibers were found to be similar. Following bilateral superior cervical ganglionectomy, 5-HT-LI fibers were not detected in pial vessels even after incubation with 5-HT. Light-microscopic autoradiographic examination of [3H]-5-HT uptake in pial arteries showed that silver grain granules were concentrated only in the unmyelinated nerve profile in the adventitial layer. No uptake of [3H]-5-HT into smooth muscle cells and endothelial cells was found. The neuronal uptake of [3H]-5-HT was blocked by imipramine. Results from ultrastructural studies also showed that 5-HT-like immunoreactivities were found only in the axoplasm and were never detected following chronic superior cervical ganglionectomy. These results indicate that the presence of 5-HT-containing nerves in pial vessels in various species examined is due to the uptake of 5-HT into sympathetic nerves, and further support our hypothesis that cerebral pial vessels do not receive authentic serotonergic innervation. The present study also identifies the heterogeneity in characteristics of smooth muscle and endothelial cells among cerebral and peripheral arteries.

Xylamine enhances pineal gland N-acetyltransferase activity in vitro

1. 1. The action of N-2′-chloroethyl- N-ethyl-2-methyl benzylamine (xylamine) on rat pineal gland sympathetic innervation was examined. 2. 2. This alkylating agent caused a concentration-dependent increase in pineal gland N-acetyltransferase (NAT) activity in neurologically intact pineal glands that was suppressed in glands previously subjected to bilateral superior cervical ganglionectomy. 3. 3. Xylamine-induced elevations in NAT activity were attenuated by β-noradrenergic antagonist drugs but not by α-noradrenergic antagonist drugs. 4. 4. Since pineal gland uptake of radiolabelled norepinephrine (NE) was impaired by xylamine, the drug may increase pineal gland NAT activity by inhibiting NE reuptake into the presynaptic nerve terminal, thereby increasing the amount of the neurotransmitter available to stimulate pinealocyte β-noradrenoceptors.

Neuropeptide Y: vasoconstrictor effects and possible role in cerebral vasospasm after experimental subarachnoid hemorrhage

The possible role of neuropeptide Y (NPY) as a vasoconstrictor substance contributing to the development of cerebral vasospasm after experimental subarachnoid hemorrhage was studied. Autologous blood was injected into the cisterna magna of control rabbits and rabbits that had received bilateral superior cervical ganglionectomy 2 days before blood injection. The days after blood injection the concentration of NPY in cerebrospinal fluid (CSF) was 5971 ± 551pg/ml while CSF from control animals contained992 ± 162pg/ml of NPY. The effects of porcine NPY on norepinephrine-induced contraction of rabbit cerebral arteries were also studied in vitro. NPY (1.2 nM) caused a 3-fold potentiation of norepinephrine-induced contraction of cerebral arteries. CSF from control rabbits diluted by 50% with Krebs solution had no significant effect on norepinephrine-induced contraction of cerebral arteries when compared to responses in Krebs solution only; however, diluted CSF from denervated blood-injected rabbits potentiated norepinephrine-induced contraction by 2.6-fold. Antiserum containing NPY specific antibodies was used to immunoprecipitate the peptide from CSF taken from denervated blood-injected rabbits. CSF treated with this antiserum contained less than 40 pg/ml of NPY and had no effect on norepinephrine-induced contraction of cerebral arteries. These results show that the concentration of NPY in CSF of rabbits is elevated after experimetal subarachnoid hemorrhage. In addition, NPY in CSF can potentiate the vasoconstrictor effect of norepinephrine which may contribute to the development of cerebral vasospasm.

Immunohistochemical demonstration of tyrosine hydroxylase (TH)-positive but dopamine β-hydroxylase (DBH)-negative neuron-like cells in the pineal gland of golden hamsters

Double immunostaining for tyrosine hydroxylase (TH) and dopamine β-hydroxylase (DBH) in the pineal gland revealed many TH-positive but DBH-negative, neuron-like cells in golden hamsters, but not in rats and gerbils. They were scattered in the meshwork of TH- and DBH-positive nerve fibers throughout the parenchyma. Their cell bodies were oval or spindle-shaped (maximum diameter: 15–20 μm). They had sometimes one or two short cell processes. Bilateral superior cervical ganglionectomy diminished strikingly the number of TH- and DBH-positive nerve fibers, but did not affect the number of TH-positive cells.

Relation of supersensitivity to cerebral vasospasm induced by oxyhaemoglobin.

There have been reports that superior cervical ganglionectomy (SCG) is effective as a treatment for cerebral vasospasm following subarachnoid haemorrhage (SAH). On the other hand, denervation supersensitivity is supposed to play an important role in vasospasm. The two accounts contradict each other. To investigate this problem, various examinations were performed using the exposed basilar arteries of cats. We have accepted that oxyhaemoglobin (Oxy-Hb) is an important spasmogenic substance. Therefore, the change in vascular reactivity to Oxy-Hb was investigated after various kinds of denervations. It was confirmed that Oxy-Hb has no adrenergic receptor agonist properties because the Oxy-Hb inducing vasospasm was not suppressed by Prazosin or phenoxybenzamine. As a result of this, it is not likely that augmentation of Oxy-Hb inducing vasospasm is caused by deviation supersensitivity. Thus, the non-deviation supersensitivity became a topic of investigation. The basilar arteries were denervated by chemical treatment (reserpine, 6-hydroxydopamine) or bilateral SCG to examine the change in the reactivity to noradrenaline or Oxy-Hb. An increase in reactivity to noradrenaline was observed with the denervations. In contrast, no change in reactivity to Oxy-Hb was found. In conclusion, it was observed that deviation and non-deviation supersensitivity do not participate in vasospasm, in so far as vasospasm is caused by Oxy-Hb.

Brain Stem Terminations of the Trigeminal and Upper Spinal Ganglia Innervation of the Cerebrovascular System: WGA-HRP Transganglionic Study

The central projections of the nerve fibers innervating the middle cerebral and basilar arteries were investigated by transganglionic tracing of wheat germ agglutinin conjugated with horseradish peroxidase (WGA-HRP) in the rat. WGA-HRP was applied to the exposed basilar and/or middle cerebral arteries. Sections of the brain, trigeminal and upper spinal ganglia were reacted with tetramethylbenzidine for detection of the tracer. The results demonstrate that trigeminal neurons that innervate the middle cerebral artery project to the trigeminal main sensory nucleus, pars oralis, and the dorsocaudal two-fifths of pars interpolaris of the trigeminal brain stem nuclear complex. Terminals were also visible in the ipsilateral nucleus motorius dorsalis nervi vagi (dmnX) and in the lateral nucleus tractus solitarius (nTs) bilaterally at the level of the obex. The ventral periaqueductal gray, including the dorsal raphe and C2 dorsal horn, were also innervated by nerve fibers from the middle cerebral artery. Ipsilateral trigeminal rhizotomy prior to WGA-HRP application over the middle cerebral artery impeded the visualization of nerve terminations throughout the brain stem. Pretreatment with capsaicin reduced the density of labeled neurons and terminals within the trigeminal ganglion and the brain stem, respectively, following WGA-HRP application over the middle cerebral artery. Basilar artery fibers terminate in the C2 dorsal horn, the cuneate nuclei, dmnX, and nTs bilaterally. A few projections were also labeled in the ventral periaqueductal gray. Unilateral upper two spinal dorsal rhizotomy prior to WGA-HRP application over the exposed basilar artery resulted in terminal labeling within the C2 dorsal horn, the cuneate nucleus, dmnX, and nTs contralateral to the rhizotomy, whereas the ipsilateral side was devoid of any labeling. Bilateral superior cervical ganglionectomy prior to WGA-HRP administration to the middle cerebral and basilar arteries did not alter the visualization of nerve terminations throughout the brain stem.